1. Field of the Invention
The present invention relates to an arrangement for generating a sawtooth current having a stroke period and a flyback period through an inductive load, said arrangement comprising said inductive load, a storage capacitor, a unidirectional device through which said sawtooth current flows during a first part of each stroke period, a controlled switch through which said sawtooth current flows during a second part of each stroke period, a flyback capacitor connected in parallel with the main current path of said controlled switch, and a pulse source for supplying a pulse train for controlling the switching of said controlled switch.
2. Description of Related Art
Such arrangements are well known and can take the form of a line deflection stage where the inductive load is formed by the line deflection coils and the storage capacitor is formed by the scan or trace capacitor. A stage of this type is normally arranged to operate at a single line frequency with a fixed flyback period being determined by the inductance and capacitance in the circuit and principally the flyback capacitor. When such a deflection stage is used for data graphics display, there might be the requirement that the flyback time may be changed due to different input signal requirements. One example of this could be where the line frequency may be changed from time to time, in which case the flyback period would also need to be changed to achieve a given flyback period to scan period ratio. Such changes to the flyback period have in the past been achieved by changing the value of the flyback capacitor which can also require a switching arrangement to effect the change of capacitance which would give a single defined flyback time for each capacitance value.